ITTSB.EU Blog Forum
Electrical Metrology | Measurement Tips & Products | Calibration standards => Electrical Metrology for enthusiast => Topic started by: Kiriakos GR on August 11, 2019, 12:35:54 PM
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At several documents we read about Resistance measurement and Dry circuit (Definition).
Even at some benchtop multimeter their Resistance measurement mode this is described as Dry circuit.
Thanks to GW Instek documentation this be hidden in to a resistance meter user guide, now I can deliver their explanation in to a wider number of readers.
In theory this Dry circuit it is actually one pack of measuring circuit electrical limits.
The need of Dry circuit this is relative to low resistance measurements and especially for the application of measuring contacts resistance.
Bench top multimeter with lower measuring range of 10 Ohm up to Max 50 Ohm range they are the only candidates that can have the ability of Dry circuit and only if this feature was added by their manufacturer.
Dry circuit testing is for switch and connector contact resistance.
Switch and connector contact resistance measurement is in accordance with DIN IEC 512 and ASTM B539 which requires that the open circuit voltage of the measuring device should not exceed 20mV DC.
Voltage at such low levels avoids the breakdown of any oxides that may be present on the contacts.
In this mode the open circuit measuring voltage is limited <20mV, while modes like DC+ or Pulse mode can have an open circuit measuring voltage as high as 6.5V
ITTSB Note: Resistance measurement with Pulse mode, this is an option found exclusively at dedicated resistance meters.
Pulse mode instead of constant current, this will help low in watt resistors to not heat up under measurement and this translates to minimized influence of temperature coefficient factor. ;)